Better Mixes with EQ Notching

I can’t remember when it was that someone first said to me that as an engineer, if they had to choose one and only one effect to work with, it would be EQ. I found that over the years, a lot of engineers echoed that little bit of wisdom.

If you’re a new engineer who has recently just started delving into having your own project studio, you might make the mistake of believing you don’t need to do much to your mixes if you have used a lot of virtual instruments, or the suite of preset plugins that come with your DAW software. That would be a mistake.

Here’s why. Fundamentals, Partials, Harmonics and Overtones

As you layer tracks in your recording, you might find quickly that some of the tracks occupy the same space – not just your stereo spectrum, the perceived space from left to right and front and back – but your frequency spectrum. In fact, it’s not difficult at all to get towards the end of a mix and find that vocals, backing vocals, guitars, keyboards, and other mid range instruments are all competing for attention in the middle. Even a bass with a primary frequency range in the 60-200 Hz range can occupy a lot more space than just in the lower frequency spectrum.

The reason is that every tone in the musical frequency spectrum contains layering harmonic tones, or overtones. The primary tone or frequency is called the Fundamental. Overtones are other wave components above the fundamental. All of these components together are called partials. The spectrum of overtones with the fundamental are called the harmonic series.

Let’s say you have two instruments. One is playing a fundamental at 200 Hz. It’s harmonic series will be (200,) 400, 600, 800, 1000, 1200, …

The other, with a fundamental frequency of 300 Hz will have harmonics at (300,) 600, 900, 1200, 1500, …

The two instruments share the harmonics 600 and 1200, and there will be others further up the spectrum.

So…yeah…what a mess. And that’s only two fundamentals. All of your other fundamentals will come together and add their harmonic series, leaving you with a whole lot of overlapping harmonics to try to make distinct in your mix.

Achieving Space through EQ Notching

There is only one solution to the above problem – and it isn’t moving your faders up and down. The solution is finding a unique spot in the complete range for each of your tracks to occupy to minimize fundamental and harmonic overtone layering.

I like to do this step once I have complete most of my tracking, added cool effects, and figured out (mostly) the sections of my mix – meaning – which instruments take a lead position in the mix during which part of the song.

Once I’ve done this – which means I’ve built the “song” part of the mix, I like to start at the bottom, with the bass and kick drum, and start notching.

I’ll start by adding an EQ plugin to both the bass and kick tracks. And then I’ll open them side by side. Like this:

Insert 1

Soloing the bass, and using the EQ pointer in position 1, I’ll sweep the lower frequencies while the track plays to determine where it’s fundamental sits. I also check for spots in the sweep where there isn’t much change, and where a boost sounds bad. At this point, knowing my studio and the frequency range, I will probably add a low-pass to eliminate anything below 20 Hz, carve out a section of the middle frequencies, where I know things will get muddy later, and slightly boost it at 2kHz, where basses typically achieve some of their attack.

Now, while soloing the kick, we do basically the same thing: sweep and check for the fundamental and weak areas.

After doing this, I would play the two tracks together with their EQs open, experimenting with boosting different frequencies in either of the tracks so that instead of occupying the same space, they compliment each other. Based on how these two tracks sound together, after I’ve made these changes, the EQs look like this:

Insert 2

You continue this process moving up the frequency range. When you get to the middle, there may be a whole lot of work to do. But keep experimenting and working with your EQs to find the notches for each instrument in your mix, providing each with a space where they get to shine mostly alone. Obviously, this process is additive, so you may need to adjust as you continue adding tracks.

This process will make your mixes sound more open and clear. And you will find that you need to worry less about minor fader movements that suddenly mask that super cool guitar effect in the background you hoped would peak out.

The last thing I will do on a mix is walk away from it. Give it a few days or even a week and come back to it with fresh ears. This will allow you to figure out whether your choices were totally whack, and what still needs adjusting.

Mixing is a fine art. And EQ notching – like everything else – takes practice. Keep on working it mix after mix and you’ll eventually have a technique that will never let you down.